In a conventional elevator group-control device for a double-deck elevator, for example, at an upward operation, when a same-direction assignment detection means detects that an up landing call of the 6th floor is assigned to an upper car and an other-car car-call presence/absence determining means determines registration of a car call of the 6th floor for a lower car, an assignment changing means changes the assignment of the up landing call of the 6th floor from the upper car to the lower car to deal with both calls by a single stop (for example, refer to Patent Document 1).